The present invention relates to a wireless communication system.
One type of a wireless communication system known in the prior art is an electronic key system that performs wireless communication between a vehicle and an electronic key to permit the locking and unlocking of a vehicle door and the starting of the engine.
Various improvements have been made to further develop the electronic key system. For example, Japanese Laid-Open Patent Publication No. 2005-9200 describes an electric key system in which a vehicle transmits an information signal, which includes vehicle information such as a battery level or fuel level, to an electronic key through wireless communication. When the electronic key receives the information signal from the vehicle, the electronic key recognizes the vehicle information from the signal and shows the recognized vehicle information on a display of the electronic key. This allows the user to obtain vehicle information from a location remote from the vehicle.
In the electronic key system described in Japanese Laid-Open Patent Publication No. 2005-9200, the vehicle information is transmitted on a wireless signal. Thus, the amount of vehicle information that can be transmitted on the wireless signal is limited. For example, an information signal including information on the level of the vehicle battery can be transmitted through wireless communication. However, it is difficult to transmit, through wireless communication, an information signal indicating the procedures that should be taken when the vehicle battery is drained. To resolve this problem, the procedures can be stored beforehand in a memory of the electronic key and shown when necessary. In this case, however, the electronic key would require a display and a memory having a large storage capacity. This would adversely affect the portability of the electronic key and is thus not preferred. Further, the same applies when the electronic key shows the procedures that should be taken in accordance with the state of the electronic key, such as when the battery of the electronic key is drained.